Knock Sensor on a 2 Valve 4.6

A knock sensor is basically a microphone and the sound you hear from detonation is engine parts ringing as if they were struck with a hammer. The microphone (sensor) feeds audio information to the PCM for signal processing.

As you can imagine, a microphone attached to an engine is going to hear a lot of stuff and the output would be quite complex. A knock sensor front end in the PCM processes the signal by running it through what's known as a "band pass filter" -- a filter designed to allow only a certain range of frequencies through -- that is tuned to the characteristic frequency(s) of what knock sounds like in the engine in question.

You can buy silicon to do this in the form of a chip like the Texas Instruments TPIC8101 or you might consider obtaining the PCM from a Grand Marquis which will already have all that signal processing in place and then adjust the tune to suit your car. It's quite likely your OE PCM also has that capability and just needs the wire(s) run and the tune adapted to "activate it" ... check with your tuner.

that would be BA if you can get that to work somehow... at least you would then know when to add more methanol... ;D

sneaky98gt said:

So, I'm putting a PI 4.6 motor into my 98 GT. The new motor came out of an '01 Grand Marquis, which came with a single knock sensor. I've got 2 questions.

1. Would it be a feasible idea to hook the sensor up to an LED inside the car to let me know if it is pinging? How exactly would you wire it up? i.e. is the sensor powered somehow?

2. What kind of voltage does the sensor produce when experiencing knocking? Or is it just an on/off type of deal? I read somewhere that it only produces millivolts, in which case I do not know it could be used like I'm looking to do.

Click to expand...

Piezoelectric sensor - Wikipedia, the free encyclopedia

Keep in mind that knock sensors can often pick up other noise and falsely indicate knock. Noise from accessories, the drivetrain or other components can signal the knock sensor. In theory, it is a great idea, but even OEMs have a lot of difficulty finding a good location and doing the programming to make the sensor work effectively.

sneaky98gt said:

So, I'm putting a PI 4.6 motor into my 98 GT. The new motor came out of an '01 Grand Marquis, which came with a single knock sensor. I've got 2 questions.

1. Would it be a feasible idea to hook the sensor up to an LED inside the car to let me know if it is pinging? How exactly would you wire it up? i.e. is the sensor powered somehow?

Click to expand...

If you don't necessarily need PCM intervention to pull timing out and only want to visualize knock, check out:

KnockLink G4 - visual detonation warning — Link Engine Management Systems - plug-in & wire-in aftermarket ECU's

I can't vouch for it but maybe it's what you're looking for.